This invention relates to a vacuum system for incorporating a fuel stabilization unit (FSU) into a turbine engine for use on an aircraft.
It is common practice to use fuel as a cooling medium for various systems onboard an aircraft. The useable cooling capacity of a particular fuel is limited by the formation of insoluble products referred to as “coke”. The formation of coke deposits is dependent on the amount of dissolved oxygen present within the fuel due to prior exposure to air. Reducing the amount of oxygen dissolved within the fuel decreases the rate of coke deposition and increases the maximum allowable temperature of the fuel.
FSUs are utilized in turbine engines to remove dissolved oxygen from a fuel supply. One method of removing dissolved oxygen from fuels is using a membrane de-oxygenator. In a membrane de-oxygenator, fuel is pumped along an oxygen permeable membrane. As the fuel passes the membrane a vacuum created on the opposing side of the membrane pulls oxygen and other contaminants out of the fuel and through the membrane. The contaminants pulled from the fuel result in a mixture including oxygenated hydrocarbons. Although the overall level of the discharge is fairly small, the mixture is an environmental safety hazard and cannot be discharged into the atmosphere.
Using an oxygen permeable membrane to remove the dissolved oxygen from the fuel requires the creation of a vacuum within the fuel stabilization unit. Due to the quality of vacuum required, a multi-stage vacuum pump must be used. Multi-stage vacuum pumps are expensive and add to the overall weight of the aircraft. As can be appreciated, space aboard an aircraft is limited and any increase in device size affects overall configuration and operation.
An apparatus and method for creating a vacuum in a fuel stabilization unit and for handing the discharge from a fuel stabilization unit is needed.